Can you use multiple rigs in Blender
You can have as many rigs as you like it is pretty much the same as adding objects. You might be confused when you started your animation in the Timeline. You will only see the keyframes of the selected object. 

I would recommend to learn about Actions ( parts of an animation like: walk, jump etc.) and the NLA-editor this allows you to reuse already created actions to assemble an animation from actions.